The present invention relates to a steam-foam drive.
A steam-foam drive is a common enhanced oil recovery process. Typically, steam is injected into the lower portion of a subterranean oil-bearing formation through an injection well to enhance the production of heavy oil at a producing well. Due to buoyancy forces, steam tends to override the oil saturated zones. At maturity, a steam zone substantially depleted of oil is formed near the top of the formation. The bulk of subsequently injected steam tends to traverse the subterranean formation through the oil depleted steam zone--with a consequent reduction in oil production.
Proximate the time of steam breakthrough at the producing well, a steam-foam drive is initiated by mixing a surfactant and optional ingredients (e.g., noncondensible gases) with the steam and injecting the mixture into the formation at the same location where the steam was previously being injected. The steam-foam drive tends to increase oil production.